Characterization of the Boundary Layer in Arizona during the North American Monsoon at the Walnut Gulch Site

Abstract

The planetary boundary layer (PBL) is the lowest layer of the atmosphere, which is in contact with the surface of the Earth. The height of the PBL as it grows and decays over the diurnal cycle is a key parameter for many atmospheric processes. The Haar wavelet covariance transform is a technique for finding this height value from LIDAR backscatter profiles. Using this, ground based measurements can provide high resolution local time series of PBL height which can be used to characterize the boundary layer. This method was used to produce a PBL height dataset at the USDA ARS Walnut Gulch Experimental Watershed (WGEW) in Tombstone, AZ over several recent summer monsoon thunderstorm seasons. WGEW is a site with a long term record of hydrological and meteorological measurements The arid environment, complex terrain and vegetation variability at the WGEW provides an interesting case for study of temporal and spatial variations of the convective PBL in such an environment, and their correlation to the development of summer air mass thunderstorms. This research will focus on correlating PBL height with related variables of heat and moisture fluxes in the area, as well as precipitation rates, drop size distributions and potentially stable isotope content of rain and ground water.